


oh brother

by bluebluewater



Category: Undertale (Video Game)
Genre: Ecto-Genitalia (Undertale), M/M, Resolved Sexual Tension, not beta read at all lol
Language: English
Status: Completed
Published: 2020-08-11
Updated: 2020-08-11
Packaged: 2021-03-06 11:28:16
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,004
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25848811
Author URL: https://archiveofourown.org/users/bluebluewater/pseuds/bluebluewater
Summary: After getting stuck in Undertale, red can't help but notice sans' younger brother. More specifically, he can't help but notice how he likes to prance around in really short shorts.
Relationships: Papyrus/Sans (Undertale), UT!Papyrus/UF!Sans
Comments: 6
Kudos: 53





	oh brother

The first day was too much of a rush for red to notice it.

When they arrived in this universe there was a lot to figure out, like stupid nicknames, for example. There was a lot of back and forth on where they would stay, and King Asgore (who they reluctantly met with), had offered them hotel rooms, but Edge (god what a name), had gracefully declined. One day in this mushy world was nowhere near enough to make them accept charity from the king - even if he wasn’t their king. 

While his brother wanted to get back to their own universe, red was happy as a clam here. Of course he’d follow his bro anywhere, but that didn’t mean red was going to help.

So on the second day, when red was lounging on the couch with sans (it was gonna take some getting used to, calling someone else by his name), red noticed. 

It was Sunday - cleaning day. Papyrus was bustling around the house, tidying everything that was dirty, and even things that weren’t. He hummed cheerfully while he did it, headphones securely over his skull. 

red couldn’t help but be distracted from the TV, choosing instead to watch something much more interesting. Papyrus’ cleaning attire consisted of very short shorts, a long, old T shirt, and a bandana tied around his skull for good measure. As he danced around the living room in his tall pink socks red couldn’t look away. 

He was finally spared when Papyrus moved to another room to clean, completely unaware of his audience. sans jerked when red tapped his chest with the back of his hand, raising a brow at him as red stared in the direction the skeleton had gone.

“dude, your brother’s fuckin hot.”

Snorting in surprise, sans shoved red away from him with a foot, settling deeper into the couch. “knock it off,” was all he said, and that was that. 

Sundays soon became his favorite day of the week. It got to the point where on Sunday morning, red would be the first into the kitchen to make breakfast. And if he so happened to get the kitchen a little extra dirty, so what? He was a sans! 

His favorite pastime was sitting at the table with his feet kicked up so he could watch Papyrus scrub every inch of the kitchen. The tall glass of milk would always make sure to reorganize every cupboard as well, kneeling down to reach the lower ones. When he reached to grab forgotten dishes in the back his shirt would slide up a bit, showing off the curve of his spine and his cute shorts. Sometimes red would have to dismiss himself a little early.

Both Edge and sans noticed his little infatuation, and while sans didn’t say much about it if he wasn’t crossing lines, Edge was very clear that he was being crude. red felt somewhat guilty for watching Papyrus in a way he might not be comfortable with, but guilt was always replaced with lust, and red never had much willpower. 

red tried to rationalize that it was just a little treat at the end of the week, something that only happened on Sundays, but it very quickly spilled into the rest of his life. He started to become hyper aware of where Papyrus was and what he was doing when they were in the same house. He soon had most of the skeleton’s outfits ranked from his favorite to least favorite. And they weren’t all what appealed to him sexually, thank you. Sometimes he liked an outfit just because it looked handsome on him. 

Being in close proximity to sans’ brother made him more of a sweaty mess than usual, so much so that Edge told him Papyrus had asked about his anxiety, if he was seeing anyone about it. That made red laugh - back in Underfell no one would have ever thought he could even get nervous. Papyrus did weird things to him.

Despite wanting to distance himself from the skeleton in order to not freak him out, Papyrus and red became somewhat decent friends. The skeleton was just so darned charming that red could never deny him to hang out. They had some pleasant talks late at night when neither could sleep, bonding over crappy television. 

As their friendship grew, so did the guilt. It had returned in full force, to the point that red began to dread Sundays instead. He had started to leave the house or shut himself in the guest room he and Edge were sharing, desperate to shut his brain off. 

The guilt made him feel weird. In Underfell, he wouldn’t have thought twice about lusting after someone. Even if he never made a move to sleep with them, he was just the type of person to not really care what others thought, or how they felt. Now, he wasn’t a complete piece of shit, but ever since he started to get to know Papyrus, he could feel himself becoming a slightly better person and he hated it. But he also wanted to be as great as he could, for Papyrus. 

So he shut himself in his room on Sundays. Edge worked those days, but sans and Papyrus were home. sans was off doing whatever he did and Papyrus was doing his usual cleaning. Now, he had never bothered with the guest room before, seeing as how Edge kept it tidy, but red’s brother had been putting in a lot of hours at work recently, so the cleanliness had started to slip a bit. 

red was lounging in the bed, playing on his phone when Papyrus knocked. It had to be Papyrus, it wasn’t sans’ usual two knocks to set up a joke. Frozen in bed, red sat up and stared at the door, snapping out of his trance when he knocked again.

“uh, come in.”

Papyrus burst into the room, cheery as always. “Hello red!” he greeted with a warm smile. “It has come to my attention that while your brother is off being busy he hasn’t had much time to clean,” he was already scanning the room, finding things that needed picking up. “But! No worries!” His attention was back on red, “I, being as great as I am, will help you!” Papyrus beamed, then set to work without a word from red.

“uhm. okay,” he muttered weakly, sitting against the headboard as he watched Papyrus bustle around. 

It seemed as if lately the shorts had been getting shorter somehow. Today’s pair were some loose blue and white pajama shorts. They barely covered the tops of his femurs, and red had to keep himself from choking when he saw the bare magic of Papyrus’ legs. sans had explained to him at one point that Papyrus had so much energy stored up, he sometimes summoned an ecto body just to burn some of that magic off. red had only seen it a couple of times but even once was enough to give him wet dreams for life. 

So red did his best to keep his eyelights away from his legs and butt, while Papyrus worked on, oblivious. With the rest of the room clean, Papyrus turned his critical eye to the bed, squinting at it as he thought. Finally he started toward red, who jerked back when Papyrus shooed him off the bed. 

“I need to make the bed!” came his explanation, and red scrambled off, away from Papyrus, who simply shook out the blankets and sheets, smoothing them down. Climbing on top of the bed, Papyrus rearranged the pillows to his liking, tilting his head this way and that while he decided the best combination for maximum comfitude. 

The image of Papyrus kneeling on his bed in those shorts had red’s magic stirring, and he willed him to hurry up and leave, so he wouldn’t see anything suspicious. 

Finally, after what seemed like forever Papyrus crawled off the soft bed, hopping to his feet. He took one last look at the room before nodding to himself, leaving as quick as he came in. Sighing, red collapsed on the freshly made bed, magic tenting his shorts.

Red always tried to prevent his fantasies from manifesting physically, and when he couldn’t help it he always took care of it in the shower, where it was unlikely to bother anyone. But god, he didn’t think he could wait. His magic was achingly hard and hey, it’s not like Boss would be home anytime soon. sans and Papyrus didn’t really bother him when he clearly didn’t want to be bothered, so he definitely had a bit of time.

Sighing, red closed his eyes and let his hand slide toward his shorts. He grabbed his dick from the outside, tilting his head back at the sensation before wriggling his shorts down enough to free himself.  
He wasn’t sure whether Pap would prefer a dick or pussy, so red always went back and forth. While he stroked himself he thought of sneaking up behind Papyrus while he was organizing cupboards, gripping his hips so he could grind himself on his clothed cunt. Papyrus would squeak in surprise and attempt to wriggle out of his grasp, but soon enough would be whimpering, rocking himself onto red. He’d be so frustrated that his shorts were still on that he’d beg red to fuck him. And how could red deny him?

Jerking his cock in short, quick motions, he breathed heavily, holding back moans as his imagination started to get the better of him. 

He pulled Pap’s shorts to the side, just enough to line his dick up. “See whatcha do to me?” he growled and penetrated that sweet magic. Papyrus was noisy, his high pitched moans filling the kitchen as he was fucked, still bent over, his hands his only support on the floor. 

As the red in his fantasy began to enter harder, their magic slapping together, the red currently masturbating by himself matched their pace, his grip brutal. He tossed a hand over his mouth, attempting to stifle the increasing moans as he got closer. red had always been one to get himself off quickly and efficiently. He didn’t see the point in trying to draw it out, but even as he approached his end he found himself wanting to savor it. Of course there was no way he could, not now, but he wasn’t looking forward to the wave of guilt that always came crashing down on him after. He just wanted to feel good right now. 

With a cry, red came in Papyrus’ cunt, soaking him even further. The other skeleton was gripped tight onto him, his expression furrowed in ecstasy before relaxing, coming down from his high.

When red opened his eyes, he stared up at the ceiling, breathing heavily as he tried to ignore the quickly cooling cum covering his hand. He could really go for a nap, but Edge shared this bed with him, and he wasn’t so mean he’d soil their shared property. With another sigh, he rolled off the bed, checking to make sure there was no mess before he wandered into the connecting bathroom to wash his hand off. 

~x~x~x~

On Saturday it’s just red and Papyrus in the house. sans was out with Grillby and Edge got dragged away to some mandatory camping trip for the weekend. ‘To bond’, he had quoted Undyne sorely as he packed. 

Scratching the wing of his pelvis, red yawned, only now joining the waking world at 12:45pm. His only goal was to go get some food, but he was abruptly stopped when he turned the corner, only to find Papyrus in his usual cleaning clothes at the sink, scrubbing furiously at a stubborn plate. 

The skeleton had his headphones perched upon his skull as usual, and red was ready to sneak back out the way he came, but when Papyrus turned to place the dish on a towel to dry, he caught sight of red. Beaming, he wiped his hands on an extra rag lying nearby before tugging the headphones down. 

“Good morning red! Or, well. Afternoon!” taking advantage of his dry hands, he began to dry some of the dishes. “How did you sleep?”

“okay,” he muttered, cautiously moving past him to open the fridge. His SOUL was suddenly churning anxiously, and he wasn’t all that hungry anymore, but he took a carton of juice out of the fridge, drinking straight from the container. 

Papyrus made an offended noise and red smirked at him, smacking his mouth in satisfaction. Somehow, without eyepips, Papyrus still managed to roll his eyes, but there was a small smile on his face as he turned back to drying.

“why’re you cleanin on a saturday?” red drawled, leaning against the counter to watch him work as if he were only curious. Drying the last dish, Papyrus set them into their respective spots nicely before returning to the sink, where a tub full of dishes awaited him.

“Well, as much as I love my brother, he has a habit of becoming a nuisance whenever he senses work in a five mile radius,” he squinted his eyesockets at the dishes, before his expression brightening to it’s default. “So I thought I’d take advantage of this free time!”

“don’tcha got any hobbies?” red picked at his teeth casually with his pinky finger, watching Papyrus’ hands as they scrubbed in a hypnotizing pattern. 

“Oh, of course! But I do like cleaning!” Papyrus shrugged one shoulder, rinsing the dish before placing it on the towel next to him. "Perhaps while you’re here you could help me dry dishes?” Before red could even open his mouth to protest, Papyrus looked at his grimaced face and rushed on. “You’d just have to dry and stack them on the counter, I can put them away. I’d get done so much faster,” he said, almost pleading. No, he was definitely pleading. He even turned that puppy pout on red and that was just unfair. 

“fine, fine,” red groaned, mostly for theatrical effect as he goes to grab the rag Papyrus dried his hands with. “after all this work i might need a nap, though.”

“you truly are another version of sans,” Papyrus rolled his eyes...somehow, again and they both got into their work. The kitchen was draped with a comfortable silence, the only sound was that of dishes clanging against the sink and each other. 

Sure enough, they finished quicker than Papyrus would probably have been able to do alone. As red finished drying the last dish, Papyrus swept past him to grab the dry ones, accidentally brushing arms with him.

Shuddering, red hoped the other didn’t notice as his magic felt tingly where he had touched, shooting arousal to his pelvis. Okay, seriously he was overreacting, it’s not a big deal. At least, that’s what he tried to tell himself, but now that he was aware of it he couldn’t stop. He could feel himself sweat as Papyrus bustled around, humming some tune in his head now that his headphones were securely on the counter.

“Oh,” he was broken out of his thoughts by the image of Papyrus frowning down at a glass vase. “This goes above the stove, I hate reaching up there.”

“didn’t you raise the height of your sink back in snowdin?” red raised a brow and Papyrus’ features set stubbornly. 

“That’s different!” He raced past red as he laughed, beelining to the stove. Red choked on that laughter when Papyrus stood on his tiptoes, stretching up to carefully maneuver the fragile vase into the cupboard. His shirt and shorts rid up a lot, showing not only the bit of bare spine not encased in magic, but his perky ass as well. 

It was wrong to look, red knew that, he was better than this, but it was like he was in shock. He couldn’t look away, at least not until Papyrus straightened, spinning around only to catch his intense expression.

“Are you okay?” Papyrus questioned, and red took a step back when Pap took one forward. 

“uh, yeah. sorry, ‘ts nothing,” he muttered, definitely sweating now. He needed to leave immediately. 

“You seem feverish!” Striding toward him before he could react, Papyrus placed the back of a skeleton hand to his forehead. He frowned, moving his hand a little before sighing. “It’s always so hard to get an accurate temperature reading from a skeletons skull,” he shook his head before looking hopefully at red. “Could I possibly try your ribs? Just because that’ll work the best,” he explained hastily. Red took too long to respond, stunned, and Papyrus grunted, shaking his head even faster. “Nevermind! I’m so sorry, that was way too personal to ask-”

“i dun mind,” red heard himself say, internally screaming. He should say no, should walk out of there and never see Papyrus again but when Papyrus smiled and snuck a hand under his shirt, he couldn’t tear himself away. 

He definitely had a boner now, and red hoped the track shorts he had slept in hid it well enough. His ribs felt extremely sensitive, something they usually weren’t as Papyrus rest his hand there. He hummed thoughtfully as he checked for a temperature and red simultaneously hoped this would never end and that it ended right now, so he could leave. 

However, Papyrus went from a still hand to moving around, switching from the back of his hand to the palm. Slowly, the almost medical exploration turned into more fluid strokes, moving around his chest in no particular pattern. red jolted. looking up at Papyrus’ face and all at once realization flooded in.

“yer teasin’ me.”

That mischievous twinkle in his eye got brighter and he huffed out a laugh. “It took you long enough to catch on,” Papyrus muttered lowly, running his hand sensually along his ribs now that he had been discovered. “I was playing some of the oldest tricks in the book. I mean, come on, when was the last time we used a glass vase? And do you really think I organize all the cupboards every week?”

“i dunno!” red whined, offended. “i didn’ wanna scare you… off or anything,” his words left him as Papyrus moved down to his waist before bringing his hand back out of his shirt, walking them backwards until red’s coccyx bumped into the table.

Gripping his arms, Papyrus smoothed his thumbs over the heated bone, giggling. “Ha… I tend to surprise people.” He brought their foreheads together and red averted his eyes even tho Papyrus’ were closed, leaning forward to press their teeth together. They both made a small noise into the kiss and he could feel Papyrus smile against him just before a tongue swiped it’s way across his mouth. Caught between wanting to slow down and savor this and wanting to ravage the sexy person in front of him, red was helpless and let Papyrus take the lead. 

As they sloppily made out, red wasn’t sure where to put his hands. Papyrus’ were firmly on either side of his skull, keeping him in place. His hands just kinda hovered until one of his hands was taken by a larger. Directing red’s hand under his shirt, Papyrus let go and also reached down, but much lower until he was rubbing at the bulge in red’s shorts. 

A desperate noise escaped red at the sensation, and he tried his best to keep up, wanting to make the other feel good. He wasn’t inexperienced by any means, but he was so overwhelmed right now, Papyrus could probably feel his hands shaking. 

Parting with a small moan, Papyrus closed his eyes and took some breaths as red fondled his ribs. He ran his fingers lightly along the outside before dipping his fingers in between his ribs, scratching at the inside of his sternum. He rested his forehead against red’s shoulder, seeming to revel at the touch, before he pulled back and before red could blink, switched their positions.

Leaning against the table, Papyrus fixed him with a heated look that made a thrill shoot down red’s spine. red was guided to kneel between his legs, and red placed his hands on both of Papyrus’ spread femurs. As he panted against his thighs he felt the warm air blow back on his face. He watched, infatuated as Papyrus ran a finger down the obvious outline of his cunt, the fabric of his shorts already wet. “Not that I mind the staring, but you could also do something with it,” he smirked and red groaned, immediately burying his face in the crux of his parted thighs. 

Inhaling deeply, red sighed as the musky smell hit him, nuzzling the soft flesh in front of him, scraping his teeth lightly up his cunt. Papyrus huffed out a long breath, his hand gently guiding red’s skull back down to repeat the action. 

red moved the cloth out of the way to lick up some slick, moaning lowly as he gently lapped up everything he could. Papyrus sighed softly and rolled his head back as red worked on making him come apart. 

When Papyrus pushed red back he was breathing heavier. Sliding off the table, he hefted red to his feet by the front of his shirt, kissing him hard. He must’ve swapped genitals cause red could feel something hard press between them as they tangled tongues. The tip of red’s dick rested just against the base of Papyrus’, seeing as how the other was so much taller. He tried to cant his hip forward but was gripped tight by his upper arms and pushed up onto the table. 

“wait, here?” red braced himself on the cold wood, trying and failing to avoid looking at where their bodies were pressed together. He choked on a moan when Papyrus rolled his hips, their clothed dicks gliding against each other. With how small Pap’s shorts were quite a bit of his length was visible. “i-ha…i never took you for the type of guy to wanna bone in the kitchen,” red winked up at him, sweating a bit when Papyrus looked unamused. “don’t our bros eat in this kitchen too?”

“They won’t be home for a while,” Papyrus purred, leaning forward to nuzzle at his vertebrae. “Besides, tables are cleanable. Now, what have you given me to work with?” he seemed distracted feeling red up, rubbing with the heel of his palm from base to tip of red’s member, which was achingly hard by now. Thank god he always wore sweatpants or basketball shorts or this could be a lot worse. 

“whatever ya want, babe,” red went to wink again but yelped instead as his shorts were abruptly pulled down. his eyes wide. 

“It’s so pretty!” Papyrus cooed, dragging a finger over the dull barbs lining the underside of it. 

“weirdo,” red laughed breathlessly, his head tipping back to stare up at the ceiling blindly. He huffed quietly as Papyrus took his time exploring, curiously tipping it this way and that as he studied it. 

“It is, though,” he said absentmindedly, still stroking his cock while one hand trailed to his own shorts, tugging them down. red watched as he did so, taking a deep breath when he realized Papyrus hadn’t gotten rid of his pussy, just added a cock where a clit should be. “Hm,” he hummed, backing up to look at the situation red was in. “That’s no good,” he manhandled him once again to place him in a chair instead. 

red didn’t mind being moved around much, seeing as how his brother had a habit of carrying him underarm whenever he was in the way or not walking fast enough, but he was a bit impatient, just wanting to get to the main event. “you good now? or are you gonna move me to the floor next,” he joked, sweat running from his skull to his jaw. 

“Ew,” Papyrus shuddered. “I would not go that far, the floor is disgusting,” he frowned, then moved to straddle red’s lap, gently lowering himself so their dicks were touching once more. “My plan was to fuck you, but I have to admit, the bumps look interesting,” he smirked down at red’s aching dick. 

“fuck,” red agreed, groaning as he heard Papyrus talk like he never would have suspected the skeleton capable of. Everyone who knew him personally would know that he wasn’t as innocent as everyone seemed to believe, but Papyrus had always held himself with some level of dignity, sometimes depending on the situation. He would swear, sure, but to hear him talk this filthy was was at all commonplace. 

“Fuck indeed!” Papyrus smiled and took hold of red once more, raising himself slightly as he lined himself up, the tip of red’s cock resting against his entrance. red held his breath in anticipation, releasing it all at once in a moan when Papyrus finally pressed down. He whined as he was penetrated, his mouth gaping open as he sunk past the ridges on red’s dick. 

red held onto his hips for some semblance of control, shouting when Papyrus didn’t even wait before standing, drawing himself off of him until the head was barely in before dropping himself back down. Holding on was all red could do as he was fucked into the chair, Papyrus’ stamina proving true as he feverishly rocked their hips together. The chair squeaked against the tile floor with every movement but neither paid mind, even as the chair inched back until it rested against the counter. 

Now that he had support Papyrus went harder, pushing himself down desperately, his brow furrowed as he tried to figure out how to hit his G spot every time. He took some mercy on the other, leaning forward so red could cradle him, one hand on the back of his ribcage, the other the back of his skull, panting raggedly as he tried not to cum too soon.

red’s cries were a slur of a repetitive ‘fuck!’ and ‘oh god!’ mixed in with a few ‘Papyrus!’. Papyrus rode him like there was no tomorrow, his moans finally joining red’s when he found the perfect angle. Trying his best to meet his rocking, red rolled his hips in time, moving his hands back down to Papyrus’ hips for leverage. 

Gripping tightly to the edge of the counter behind red, Papyrus moved his feet up to the sides of the chair until he was hunched like a gargoyle, spreading his entrance even wider. He bounced quickly with red’s help, smashing his face to red’s collarbone when a small, slippery hand found its way to his neglected cock, keeping his grip firm and his hand still, letting Papyrus do all the work as he moved. 

From this angle red’s dick reached deeper and Papyrus started to sweat as he was fucked from multiple angles. He felt himself draw closer a lot sooner than he was used to and muttered half of a warning against red’s skull.

“yeah, yes, fuck baby,” red babbled, completely overwhelmed. “please-ngh… please can i come? let me come inside…” he growled, rocking up into Papyrus fiercely before Papyrus overpowered him again. 

Papyrus clutched red’s skull, kissing him hard before pulling back, whispering “You can come, inside,” against his teeth. red groaned, teetering on the brink as Papyrus kept his quick, heavy pace. As he barreled closer and closer his moans got louder than he had ever been and he finally came, his hands frantically rescrambling to grip onto Pap’s ass again. Whether it was to keep him still or move him neither knew, but Papyrus easily rode him through it, panting through a smile as red nearly wailed as the stimulus became too much. 

He finally stopped when red clearly was trying to push him off, sitting still on red’s lap, his dick twitching through the aftershocks inside of him. As red tried to catch his breath, Papyrus hummed nicely, laying his head down on his shoulder, his cunt pulsing in time with his magic. red leaned against him for support as they both basked in the moment. Finally regaining his bearings, red brough his hand back to Papyrus’ dick to finish the job. 

Jerking him roughly and quickly, Papyrus gasped again and couldn’t help the small twitches of his hips as the orgasm that had been ebbing was brought forefront again. It took only a few minutes until Papyrus stiffened, spilling into red’s hand, cumming hard enough that some made it to their shirts. 

Calm settled over them like a blanket as they came down from their highs, the only sound their heavy breathing and the buzzing of summer outside the window. Sighing, Papyrus finally clambered off of red, who looked half asleep. Spent magic trailed down his thighs and he grimaced, quickly fetching a rag to clean themselves off with. He maneuvered a boneless red around until he managed to strip his shirt, adding his own to the collection soon after.

“hey,” red halfheartedly protested when Papyrus picked him up once more to pad to his own bed, throwing the laundry into his dirty bin on the way. Humming sleepily, red settled down into soft blankets and Papyrus decided to stay for a bit despite needing a shower badly. Just when he thought the other was asleep, red muttered “ ‘was good.”

“I am certainly glad you thought so,” Papyrus snickered. “Now goodnight.”

“night.”

Later that evening, red was still happily snoozing away when sans came back. Papyrus cheerily greeted him from the couch, redressed, the kitchen back in order. Slouching on the seat next to his bro, they quietly watched TV for a minute before sans spoke up.

“you two finally hook up?”

“Yep! I believe you owe me, brother!” 

“yeah, yeah,” he chuckled, digging around in his inventory to throw 20G at him. “in my defense, i thought it’d take red a lot longer to catch on.”


End file.
